Aliphatic polyethers



ALIPHATIC POLYETHERS Randolph Riemschneider, Berlin-Charlottenburg, Germany, assignor to Ethyl Corporation, New York, N.Y., a corporation of Delaware N Drawing. Filed July 31, 1957, Ser. No. 675,254

3 Claims. (Cl. 260-615) This invention relates to synthetic lubricating compositions. More particularly, this invention relates to synthetic lubricants having superior performance characteristics, especially outstanding resistance to oxidative deterioration.

The large number of materials used as lubricants shows that the many different purposes of lubricant application require the choice, in each case according to the particular lubricating requirements and operating conditions, of materials which fulfill as many of the requirements as possible. However, this is not always possible. Some lubricants are not stable enough toward oxidants, corrosion, and heating; others have too low a lubricant strength and too little lubricity or cannot withstand extreme pressures. oftentimes small amounts of one or more additives compensate for these deficiencies. Also, the use of completely difierent classes of materials have been investigated, e.g., silicones, instead of lubricating oils obtained from petroleum fractions or instead of synthetic oils based on hydrocarbons or esters. The search continues for materials which have not yet been used for lubrication but which are suitable therefor and which can fill certain gaps in the previous choice of lubricants.

An object of this invention is to provide novel and highly useful synthetic lubricants. Another object is to provide synthetic lubricating compositions characterized by outstanding stability against oxidation. Another object is to provide new compositions of matter. A further object is to provide methods of eliectively lubricating relatively-moving metallic surfaces which are normally in contact with each other. Other objects will be clear from the following description of this invention.

The present invention comprises essentially the use of ethers as lubricants, particularly those organic compounds which contain several ROR linkages, wherein R and R signify the same or different hydrocarbon radicals. It should be understood that for the purposes of lubrication, only those ethers are to be considered which have high enough boiling points so that they are practically non-volatile at the usual temperature and which have an oily nature or which are solid, plasticizable substances.

It has been shown that ethers of the aforesaid type are not only equivalent to the previously known lubricants but are even superior in many respects.

Particularly useful as synthetic lubricants are ethers having a total of to 27 carbon atoms in the molecule and a boiling point at atmospheric pressure of at least 180 C., the ethers being represented by the following formulas:

wherein R, contains 1 to 6 carbon atoms and is selected from the group consisting of alkyl, alkenyl and cycloalkyl rates Patent 6 F groups and R contains 10 to 16 carbon atoms and is 2,973,338 Patented Feb. 28, 1961 selected from the group consisting of branched chain alkyl and branched chain alkenyl groups;

wherein R contains 1 to 12 carbon atoms and is selected from the group consisting of alkyl and cycloalkyl groups, R, is a divalent aliphatic hydrocarbon radical containing 2 to 8 carbon atoms and R contains 2 to 18 carbon atoms and is selected from the group consisting of alkyl, alkenyl, cycloalkyl, cycloalkyl-substituted alkyl and aralkyl groups;

wherein R contains 1 to 7 carbon atoms and is selected from the group consisting of alkyl and cycloalkyl groups, R; is an alkylene group containing 9 to 18 carbon atoms and R contains 1 to 12 carbon atoms and is selected from the group consisting of alkyl and cycloalkyl groups;

wherein R and R are alkyl groups containing 4 to 10 carbon atoms;

wherein R and R are alkyl groups containing 4 to 10 carbon atoms; 1s 2 4- 2 4 "-R14 wherein R is an alkyl and aralkyl group containing 3 to 10 carbon atoms and R contains Sto 20 carbon atoms and is selected from the group consisting of alkyl, cycloalkyl and aralkyl groups;

wherein R 5 contains 3 to 8 carbon atorns and is selected from the group consisting of alkyl and cycloalkyl-sub.- stituted alkyl groups and aralkyl groups and R contains 5 to 16 carbon atoms and is selected from the group consisting of alkyl, cycloalkyl and aralkyl groups; (')H RnO-CH2-(i3-CH2-OR11 R18 7 wherein each R is an alkyl group containing 2 to 5 carbon atoms and R contains 6 to 10 carbon atoms and is selected from the group consisting of alkyl and alkenyl groups;

(9) RnO-OH2CHCH2O-Rn wherein R is an alkyl group containing 1 to 3 carbon atoms, R contains 3 to 8 carbon atoms and is selected from the group consisting of alkyl and aralkyl groups and R contains 3 to 8 carbon atoms and is selected from the group consisting of alkenyl and aralkyl groups; (10 nito-c1ano=cn -onz .o-an,

OR23 i V wherein R22 R and R are alkyl groups containing 1 to 4 carbon atoms; a

CH1 I ethers lies between 0.8 and 3.0. The ethers can also be.

used in mixture with known lubricants. One can also use mixtures of ethers of different molecular weights or difierent molecular structure.

The viscosity and viscosity latitudes (Wp) of some of propanedioli 2 ethyl-l,3-hexanediol;' 2-amyl-2-ethyl-1,3- propanediol; 2-isopropyl-l.B-pentanediol; 2 tert-butyl-Z- isopropyl 1,3-propanediols; 2-ethyl-4-methyl-1,B-pentanediol; 2 isopropyl-4,4'-dimethyl-1,3 pentanediol; 2-hexy1- 2 methyl 1,3-propanediol; pentaerythritol; 2,2,6,6-tetramethylol-cyclohexananone; 2,2,6,6 tetramethylol-cyclohexanol; 2,2,6,6 tetramethylol-cyclopentanol; pivalyl alcohol; quinitol; inositol; tetrahydroxycyclohexane; trihydroxycyclohexane; pentahydroxycyclohexane; octadiol; tetramethylol of the formula Of the halohydrocarbons (containing chlorine, bro mine, iodine) those which are branched chain are particularly suitable. The reaction with straight chain'comthe synthesized ethers are given in the following:

Deeyl-propyl-glycol ether 4. 056 2. 248 1. 468 2.11 Dodeeyl-propylzlyeol ether 5. 646 2. 948 1.858 1. 78 Tetradecyl-propyl-glycol ether" 7. 621 3. 761 2. 295 1. 53 Hexadeeyl-prouyl-glyeol ether 10. 439 4. 831 2. 892 1. 26 Octyl-propyl-diglycol ether- 4. 413 2. 369 1. 527 2. l8 Deeyl-propyl-diglycol ether" 6. 065 3. 082 1. 912 1. 85 Dodccyl-propyl-diglycol ether 7. 975 3. 903 2. 343 1. 54 Tetradecyl-propyl-diglycolether 10. 283 4. 824 2.850 1.28 Hexadecyl-propyl-diglycol ether 13. 525 6.128 3.475 1.09 Octyl-propyl-tl'iglycol ether (i. 779 3. 278 2. 008 1. 93 Dodecyl-pronyltriglycol ether 11.330 5.146 2.929 1.36 Deeyl-propylether of bntaue-diol- 1,4 6. 206 3.116 1. 963 1. 77 Hexadecyl-propyl-ether of butanediol-l,4 14.080 6.090 3.483 1.14 Benzyl-propyl ether of butaue-diol- 1,4 4. 677 2. 408 1. 535 2. 42 Benzyl-propy] diglycol ether 5. 398 2. 706 1. 644 2. 51 Benzyl propyl triglycol ether 8.278 3. 731 2.192 2.05

The pour points of ethers with straight hydrocarbon chains are higher than the pour points of ethers with branched hydrocarbon chains. The pour points of the benzyl propyl ethers of ethanediol, diglycol, triglycol and butanediol and the pour points of the corresponding cyclohexyl and cyclopentyl compounds all lie below 30 C. r'

a branched chain nonyl-isobutyl glycol ether has a pour point below C. Iso-nonyl-isoamyl triglycol ether and isononyl-, isopropyl pentanediol ether have pour points below 25 C.

1 dissolved in 280 grams of distilled glycol.

Use has also been made of branched chain halides for reaction with alcoholates. e.g.,.

2,Z-dimethyl-octylhalide; 10,10-dimethyland 10,10-di- Alkali halide The resultant ether alcohols were then further reacted in the same manner until all the OH groups present were etherified, e.g.,

NB.oR1OR2+Ha1-R3 R30R1-0--Rz Nn Hal.

NaO on, I into on.

Na Hal.

R 0 0 R R 0 R5 The following representative alcohols can be used: ethanediol; diglycol; triglycol; tetraglycol; propanediol, butanediol; terpinol; partially hydrated dicyclopentadienediol; amyldiol; 2-ethyl 2-tert-butyl 1,3-propane'diol; 2-ethyl-. 1,3-pentanediol; 2,5 dimethyl-1.3 hexanediol; 2,4-dimethyl 1,3 propanediol; 2-rnethyl-l,3-octanediol; 2,2

diethyl 1,3 propanediol; 2-ethyl-L3-heptanediol; 2-isopropyl 2-methyl-l,B-propanediol; Z-isopropyl-l ,3-hexanediol; 2 tert-butyl-Z-methyl- 1,3-propariediol; Z-methyl- 2-neopentyl 1,3 propanediol; 2-ethyl-2-isopropy1-1,3-

pounds, as shown in the examples, likewise takes place satisfactorily. Also, mixtures of halohydrocarbons react very well with the alcoholates of the above mentioned alcohols.

EXAMPLES Within the scope of these experiments, more than ethers have been synthesized and tested for their lubrieating oil characteristics. One hundred and fifteen of these ethers are named above.

, One series of experiments on the preparation of ethers of mono-, diand triglycols is described in the following. In similar manner, we. have also prepared ethers of the other above-mentioned di-, tri-, tetra-, penta-o-ls, etc. The reactions of the alcoholates with branched chain halohydrocarbons, e.g., isohexylhalide instead of n-hexyl halide, proceed in a completely analogous manner.

(A) Octyl-propyl-glycol ether (a) n:Pr0pyl -glycol ether: 30 grams of sodium were This solution was mixed with 175 grams n-propyl bromide and refluxed until the bromide disappeared. Then, the reaction mixture was heated another one to two hours and fractionated without removing the precipitated NaBr.

Forecut: About 30 cc. of which 10 to 15 cc. is n-propyl bromide; 7 Main fraction: 149156 C.=127 g.=86 percent of y- After cut: About 10 cc. 13.1. C.

Then'the thermometer very rapidly rose up to the boiling point of ethylene glycol. The main fraction was fractionated once more whereby the main portion passed over at ISO-152 C. .7

(b) n-Octyl-n-propyl-glycolether: 7 5.1 grams of sodium (smallest pieces possible) were dissolved in a mixture of 100 cc. absolute ether. and 23.5 grams n-propyl glycol ether. The solution was mixed with 43 grams of octyl bromide, the ether was distilled off and the reaction mixture heated on a water bath for about one hour. The precipitated NaBr was filtered off and the filtrate fractionated in vacuum. The forecut distilled at 56-57 C./ 16

mm. and consisted of n-propyl glycol ether. The main fraction boiled at 132133 C./ 16 mm. Yield: 80 percent of theory. I

C13H23O2 Z Calculated: 72.2 C; 13.05 H. Found: 71.9 C; 13.13 H. Viscosities (in centistokes) 2.914 at 20C. 1.707 at 50C. 1.138 at 80 C. Pour Point: Below-35 C. Wp: 2.67.

U (B) In the corresponding manner, the following reac- :Forecut: To 180 C./ 14 mm. (small amount-octyl trons were also carried out: bromide) Ether, Propylene No. Ether Synthesized N a, g. cc. glycol Halohydroearbon B.P., C.

ether, g.

n-Decyl-n-propyl glycol ether 4. 100 20. 5 43.5 g. n-decylbromlde 159-160/16 n-Dodccyl-n-propyl glycol ether- 4. 5 100 20. 5 49 g. dodecylbroruide 182-184/16 n-Tetradecyl-n-propyl-zlycol eth 4. 5 100 20. 5 54.3 g tetradecylbromide. 184-186/5 n-Hexadecyl-n-propyl-glycol ether- 4.0 100 19.0 3.0 g cetylbrornide. 207-20917 n-Octadecyl-n-propyl-glycol ether: 3. l 100 14. 5 44.5 g. octadecylbromld 241-243/14 Benzyl-n-propyl glycol ether 5. 1 150 23. 5 29.0 g. benzyl chloride 135-136/16 Propyl-dis rc ether n-Octyl-n-propyl dlglycol ether 4 1 0 29 33 g. n-o ctylbromlda. 169-172/11 n-Decyl-n-propyl diglycol ether.-- 4 15 0 29 38 g. n-decylbromlde 186-l88ll3 n-Dodecyl-n-propyl diglycol ether 4 100 29 43 g. n-dodecylbromlde 171-173/0 9 The monopropyl diglycol ether was prepared in the following way: grams of sodium were dissolved in 160 grams of diglycol. The brown colored reaction prodnot was cooled and mixed with 53.5 grams of n-propyl bromide. The reaction mixture was refluxed on a water bath for three hours, whereby NaBr started to precipitate out after minutes. After cooling, the reaction product was mixed with somewhat more water than required for solution of the NaBr and the mixture extracted 6-7 times with ether. The ether solution was dried with Na SO the ether evaporated oil and the remainder distilled in vacuum.

Fraction 1: To 100 C./18 (small amount, odor of n-propyl glycol ether) Main fraction: B.P.=148-150 C./0.6 mm. Yield: 65 percent of theory.

' Propyl Ether Synthesized Na, g. Ether triglycol Halohydroearbon B.P. 0.)

(12s.) ether n-Dodeeyl-n-propyl-triglycol ether-J 3. 5 100 32 n-%odecylbroniide, 192104/0.9

. g. n-Tetradccybn-propyl-trlglycol ether 3. 5 100 32 n-Tetradecyl bro- 192494402 7 mide, 40 g. 192-184/0.3

Fraction 2: 100-110 C./ 18 (45.5 g.=67.5 percent of theory) Fraction 3: 128-430 C./18 (small amount, insoluble in water, soluble in ether/diglycol.

The redistilled mono-n-propyl diglycol ether boiled at 105-107 C./l8 mm. Mono-n-propyl-triglycol ether: Prepared underthe same conditions as n-propyl diglycol ether. From 315 grams of triglycol, 20 grams of sodium and 110 grams of n-propyl bromide, 127 grams of crude product was obtained after the ether was distilled off. Yield: 75 percent of theory. B.P. l4815 0' C.

(C) n-Octyl-n-propyl triglycol ether in the preparation of the diether of triglycol, the product must be worked up somewhat diiferently, since'the NaBr can be filtered oil only with large losses due to'the high viscosity of the ether.

3.5 grams of sodium (smallest pieces possible) were dissolved in a mixture of 100 cc. of ether and 32 grams of mono-n-propyl-triglycol ether. This was mixed with 29 grams of n-octylbromide, the ether was distilled oil and the reaction mixture heated for one to two hours on a boiling water bath. After cooling, the precipitated NaBr was dissolved with about 100 cc. of water and the waterinsoluble portion taken up with ether. Y The mixture was separated in a separatory funnel and thesether solution dried with Na SO After evaporation oi'the ether,,,the

remainder was fractionated in vacuum.

Besides obtaining very effective lubrication by using the foregoing others to lubricate relatively-moving, contacting metallic surfaces, excellent lubrication is also achieved when these others are used in conjunction with known lubricants. Thus, the synthetic lubricants of this invention comprise the above defined ethers, which may be used in combination with one or more standard lubricants, such as mineral lubricating oils, synthetic ester lubricants, silicones, chlorodiphenyl oils, and the like. When used in these combinationsthe ether preferably predominatesi.e., is present in the resultantcomposition in amount greater than 50 percent. However, benefits are achieved by blending one or more of the above ethers with standard lubricants even at concentrations as low as 5 percent or less. a

As further examples of this invention, use is made of the standard Lauson engine test. According to this test, a standard spark-ignition internal combustion engine is operated for 25 hours using a standard fuel. The englue is examined before and after the test and the merit ratings as to varnish formation are given according to the/test standards.- The rating scale in olves numbers from 0 to 10,0 beinga perfect rating. Thus,-this test very effectively evaluates the usefulness of the engine lubricantsubjected to the test.- Asa baseline, the engine is. operatedusing a highly-refined mineral lubricating oil having a viscosity of. 60' Saybolt Universal Seconds at 210 F. aslubricant. The test is then repeated a number EXAMPLE 1 A lubricant is formulated to contain 10 percent of lauryl polymethacrylate, percent of tricresylphosphate and 85 percent of 1-methoxy-7-ethoxy heptane.

EXAMPLE 2 A lubricant is formed from percent of lauryl polymethacrylate, 5 percent of tricresylphosphate, 0.5 percent of phenothiazine with the balance being propyl-cetyl-triglycol ether.

EXAMPLE 3 A lubricant is formulated to contain 5 percent of lauryl polymethacrylate, 3 percent of tricresylphosphate, 12 percent of highly-refined mineral lubricating oil having a viscosity of 60 Saybolt Universal Seconds at 210 F. and 80 percent of cyclopentylisotetradecyl ether.

EXAMPLE 4 A lubricant is made from 10 percent of lauryl polymethacrylate, 1.5 percent of tricresylphosphate, 0.5 percent of phenyl-a-naphthyl amine, 44 percent of di-2- ethylhexyl sebacate and 44 percent of benzyl-propyl-triglycol ether. 1

EXAMPLE 5 A lubricant is made from 6 percent of polyisobutylene, 4 percent of triphenylphosphate, 30 percent of diisooctyl azelate and 60 percent of nonyl-decyl ether of butanediol-1,4.

EXAMPLE 6 A lubricant is formulated to contain 8 percent-of lauryl polymethacrylate, 2 percent of tricresylphosphate, 70 percent of tetraoctyl pentaerythritate, and percent of dodecyl-n-butyl-triglycol ether.

The use of the above formulations as lubricants for aircraft gas turbine engines not only provides etfective lubrication, but shows that the formulations have unusually high stability under use conditions. Other formulations involving the ether lubricants of this invention will now be apparent to those skilled in the art.

I claim:

1. As synthetic lubricants, ethers having a total of 10 to 27 carbon atoms in the molecule and a boiling point at atmospheric pressure of at least 180 C., the ethers being selected from those having the formula wherein R R and R are alkyl groups containing 1 'to 4 carbon atoms, and those having the formula wherein R R R and R are alkyl groups containing 1 to 4 carbon atoms.

2. As synthetic lubricants, ethers having a total of 10 20 to 27 carbon atoms in the molecule and a boiling point at atmospheric pressure of at least 180 C., the ethers having the formula wherein R22 R and R are alkyl groups containing 1 to 4 carbon atoms.

3. As synthetic lubricants, ethers having a total of 10 to 27 carbon atoms in the molecule and a boiling point at atmospheric pressure of at least 180 C., the ethers having the formula wherein R25, R R and R are alkyl groups containing 1 to 4 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,156,724 Evans et al. May 2, 1939 2,271,873 Perkins et al. Feb. 3, 1942 2,339,476 Hearne et al. Jan. 18, 1944 2,605,292 Shugar et al. July 29, 1952 2,658,082 Urban Nov. 3, 1953 2,768,212 Copenhaver Oct. 23, 1956 2,794,029 Phillips et al May 28, 1957 OTHER REFERENCES Gretcher et al.: Jour. Amer. Chem. Soc., vol. 46 (1924), pgs. 1503-04 (2 pages) Palfray et al.: Chem. Abstracts, vol. 22 4462-63 (2 pages).

Liston et al.: Jour. Amer. Chem. Soc., vol. (1938), page 1264 (1 page) Hennion et al.: Jour Organic Chem, vol. 18 (1953), page 1606 (1 page).

(1928), pages 

1. AS SYNTHETIC LUBRICANTS, ETHERS HAVING A TOTAL OF 10 TO 27 CARBON ATOMS IN THE MOLECULE AND A BOILING POINT AT ATMOSPHERIC PRESSURE OF AT LEAST 180*C., THE ETHERS BEING SELECTED FROM THOSE HAVING THE FORMULA 